The present invention relates to a device and method for use in a manhole or similar structure, whereby the device is designed to filter contaminated gases.
Manholes are used to access underground utility and sewage systems with the manhole a conduit to the surface. Often these underground systems will have significant amounts of organic waste, as well as moisture. Such conditions are ideal for the propagation of bacteria. It is known that some species of bacteria found in manholes or sewers will metabolize organic waste. Byproducts of the metabolic process result in the bacteria forming a wide variety of waste compounds. Included among the waste compounds are hydrogen sulfide and other gaseous components, which result in odors emanating from a typical manhole. Additionally, these waste products can cause corrosion of the concrete walls which form the manhole. As such, it is desired to have a method and/or device for eliminating or treating such gases and waste byproducts.
One method for controlling the diffusion of various odiferous gases is to seal the manhole cover to prevent the escape of such sewer or utility gases. Sealing traps the various gases in the manhole. Unfortunately, this allows for the buildup of methane and hydrogen sulfide aggravating corrosion problems and creating a hazardous environment. In response, devices have been developed which allow for the free exchange of gases between the sewer or utility system and the surface. Examples of such devices include breathable manhole lids. Such lids are disadvantageous, however, because they can allow surface water and debris to enter the manhole.
Another alternative is a vented manhole lid which requires an odor control basket or device for filtration be located directly below the lid. These devices and variations thereof have been designed to treat odiferous and contaminated gases found in a sewer or underground utility system. The device includes mechanical valves or traps to allow water or debris entering through the lid to drain down into the sewer or utility pipe section. Typically, the basket is filled with compost or other gas filtration media, with the basket located in the neck of the manhole. These devices are often bolted or attached into the wall of the manhole neck so that only a small space is located between the device and the manhole neck. While useful in treating contaminated gas, such devices, and the odor control media they contain, have been reported to be fouled by surface water and debris entering through the lid. These devices, generally, work well in arid or dry locales, but when substantial rainfall is received, such devices are generally found to be inadequate. It has been observed that during a heavy rain storm, large volumes of water and debris will pass through portions of the manhole lid and into the sewer system. The basket devices or members are in the path of the water and suffer from the media being washed away, or the water ruining the media found in the basket. The loss of media and/or media contamination prevents adequate filtering of contaminated gas by the media. Also, debris caught in the basket interferes with the functioning of the media. As such, these systems are unsuited for use in regions where the rainfall exceeds that found in a desert or semi-arid region. For this reason, it is desired to have a device that can be used to filter gas in regions where there is rainfall exceeding that of an arid region.
Another problem with systems that are located in the neck relates to the corrosive or contaminated gases damaging the majority of the manhole. The gases should be filtered further down in the manhole to circumvent some of the corrosive effects. For this reason, it is desired to have a device that treats the gas prior to contact with most of the manhole. Also, not all the gas is typically treated because some of the gas can pass through the space located between the basket and the manhole neck. For this reason, a device that filters most all of the contaminated gas is desired. As such, it is desired to have a device that can be used in all geographic regions regardless of the amount of rainfall, whereby debris will not be trapped in the manhole neck, and the media will not be washed away or contaminated. Additionally, it is desired to have a device that forces all or the majority of the gas to be filtered by the media.
It should be noted that there is a risk of significant disruption of sealing of the device with the manhole wall as a result of flooding, debris accumulation, or need for personal access. When this happens, the media should be protected from water or debris and not disturbed if the device is removed and reinserted in the manhole.
Other odor control methods involve placement of above ground containers outside of the manhole, either directly on top or adjacent to the manhole. These systems can be used with or without powered movement of the sewer or utility gases from the manhole to the device. However, manholes are often placed in streets or other high traffic areas that do not allow above ground devices.
The present invention relates to a device for use in association with a sewer system or any other confined underground area whereby organic waste and moisture collect to produce gas contaminated with sulfur and other compounds. Preferably, the device can be mounted in a manhole or similar narrow tubular structure where gas typically collects or escapes through. The device will include a member for holding an amount of filtration media, whereby the contaminated gas passes through and is filtered by the media found in such member. The member should be of a sufficient size to hold an amount of filtration media sufficient to substantially eliminate contaminates found in the gas. Also, the member should be easily placed in and removed from a manhole or similar structure. Preferably, the member is a canister.
Any of a variety of different types of filtration media can be placed in the canister or similar structure. The media will be selected based on the particular contaminates desired to be removed or filtered. Generally, any of a variety of different medias can be used, including, but not limited to, metal oxides, compost, and activated and impregnated carbon.
The canister will preferably be lowered into the manhole to a position near where the gas emanates from. As such, it is desired to have a support member for use with the device that allows for the easy lowering and removal of the canister into and from the manhole. Typically, a chain or similar cable structure can be used to support the canister. It is preferred if the cable is affixed to a portion of the manhole neck on one end and to the canister on the opposite end.
Attached to the canister or similar member will be a skirt or expandable and collapsible frusta-conical member. The skirt member is desired to direct the contaminated gas to the canister for filtration. Also, the skirt member will form a light seal with the wall of the manhole, or similar structure, whereby gas is generally prohibited from passing along the sides of the skirt member, but the seal is light enough to allow water to pass along the sides. The skirt member should further be of a construction that allows it to fit a variety of diameters so that it is adjustable. Preferably, the skirt member is flexible and has a lip on one end that is inflatable to allow for the expansion of the bottom portion of the skirt to fit the diameter of the structure in which the device is placed.
The present invention is advantageous because it can be located close to the source from which the gases are produced. This, in turn, is advantageous because it helps to eliminate some corrosion and destruction of the manhole or similar structure wall. The device is further advantageous because it is not subject to damage or media malfunction as a result of a rain storm. The device is also advantageous because it can be readily adjusted and easily removed and reset.